Machines for compression molding closure shells, or compression molding sealing liners within closure shells, typically include a turret or carousel that rotates around a vertical axis. A plurality of molds are provided around the periphery of the turret in the form of male and female mold sections that are aligned along vertical axes parallel to the axis of turret rotation. Cams drive one or both of the mold sections of each pair between an open position, in which a molded part is stripped from the mold and a charge of molten plastic material is placed into the mold, and a closed position in which the mold sections are brought together to compression mold the shell or liner. In a liner machine, a premade closure shell is placed in a nest when the mold sections are open, and a charge or pellet of liner material is placed in the mold before the mold is closed. U.S. patents that illustrate machines of this type for compression molding plastic closure shells include U.S. Pat. Nos. 5,670,110, 5,989,007, 6,074,583 and 6,478,568. U.S. patents that illustrate machines of this type for compression molding sealing liners within closure shells include U.S. Pat. No. 5,451,360. U.S. Pat. No. 6,123,880 discloses a compression molding machine in which each mold has radially aligned mold cavities into which mold charges are placed by a single placement mechanism.
The present disclosure involves a number of aspects that can be implemented separately from or in combination with each other.
A machine for compression molding plastic articles in accordance with one aspect of the present disclosure includes a turret constructed for rotation around a vertical axis. A first array of compression molds and a second array of compression molds are mounted on the turret for movement through respective first and second mold paths as the turret rotates around the vertical turret axis. A first mold charge placement mechanism is disposed adjacent to the first path for placing mold charges into molds of the first array in sequence as the turret rotates. A second mold charge placement mechanism is disposed adjacent to the second path for placing mold charges into molds of the second array in sequence as the turret rotates and independently of the first mechanism. The first and second mold paths, which preferably are circular, may be spaced from each other radially of the turret axis and/or longitudinally of the turret axis.